Purpose: To compare the characteristics of choroidal transmission in punctate inner choroidopathy (PIC) with or without choroidal neovascularization (CNV) and myopic CNV (mCNV) using spectral domain optical coherence tomography (SD-OCT).
Methods: This retrospective observational case series includes 22 consecutive myopic patients (22 eyes) recruited from April 2016 until April 2018 who complained of acute blurring of vision and showed evidence of hyper-reflective material on SD-OCT imaging. Each patient underwent a comprehensive eye examination and imaging with fundus fluorescein angiography (FFA), SD-OCT, and SD-OCT angiography (SD-OCTA). Based on the results of SD-OCTA imaging and the color fundus imaging, the patients were divided into 2 groups: a group with myopic choroidal neovascularization (mCNV group, n = 10 eyes) and a group with PIC and no evidence of CNV at baseline (PIC group, n = 12 eyes). Four eyes diagnosed with PIC developed secondary PIC-CNV during follow-up. The characteristics of choroidal transmission in these eyes using SD-OCT imaging were compared.
Results: At baseline, none of the PIC lesions showed any evidence of blood flow within the lesions on OCTA imaging. However, all of the eyes with mCNV showed flow signals within the subretinal neovascularization on SD-OCTA and subretinal or intra-retinal fluid on SD-OCT imaging. These eyes with mCNV showed subretinal hyper-reflectivity associated with choroidal hypo-transmission accompanied by retinal pigment epithelium (RPE) and ellipsoid zone (EZ) disruption. In eyes with PIC inflammatory lesions, disruption of both the RPE and EZ were observed in 33% of the inflammatory lesions, and disruption of the EZ alone was observed in 67% of the lesions at the baseline. They all showed a hyper-reflective subretinal lesion located above RPE. Three cases (25%) showed evidence of choroidal hyper-transmission at the baseline, while the remaining had normal transmission within the first month after onset. Hyper-transmission then developed in all the lesions as the disease progressed. Four cases of PIC (33%) developed PIC-related CNV that showed choroidal hypo-transmission along with hyper-transmission with disruption of the RPE and EZ. In cases with PIC-related CNV, evidences of neovascularization on SD-OCTA imaging were all detected afterwards. No intra-retinal fluid was detected before secondary CNV occurred.
Conclusion: SD-OCT imaging can noninvasively differentiate and track the progression of inflammatory lesions and myopic CNV by using the presence of choroidal hyper-transmission as a sign of just an inflammatory lesion and the presence hypo-transmission as a sign of a secondary CNV, which provides a convenient strategy for diagnosis and treatment of these lesions.
Keywords: Choroidal neovascularization; Myopic; Optical coherence tomography; Punctate inner choroidopathy.